Friday, April 18, 2014
Live long enough to live forever?
Since we returned to New England from a winter on an island with little access to medical technologies, my spouse and I have been busy sorting out all those things that make life at age 77 active and enjoyable. Eye tests and glasses. Hearing aids. Dental check-ups and repairs. Prescriptions filled. Keeping the old bodies in working order.
I said to my spouse: "Just think, for most of human history our ancestors didn't have spectacles or hearing aids."
She replied: "For most of human history our ancestors were dead before they needed them."
She's right, of course. Here is a chart of the average age of death for the last 150 years. Most 30 and 40 year-olds, down there at the lower left, did pretty well with the eyes and ears they were born with. That's us at the upper right, alive and kicking, but with no help from natural selection to keep the machinery in service.
Natural selection didn't contrive eyes and ears that last longer than a few decades because it didn't have enough aged eyes and ears to work with. Life was brutish and brief, truncated by violence and disease. Gray beards and grandmas were few. Survive childhood, have sex: Those were the evolutionary imperatives. The rest was gravy.
Then along came empirical science to replace magic and the gods, and the life expectancy curve started getting more rectangular. People lived longer, then fell off the cliff at age 70-90.
The next big breakthrough will be getting rid of the cliff. Doing what natural selection couldn't do. Keeping that topmost curve flat into the indefinite future. Eliminating senescence. Practical immortality.
I won't live long enough to see it. My grandchildren might. How they and their contemporaries will solve the monumental personal, social and environmental problems is anybody's guess.
(BTW, a striking feature of the second graph above is the virtual elimination of infant mortality.)